Chemical dispersants, a mixture of emulsifiers (surfactants) and solvents, breakup oil slicks into smaller droplets and enhance the oil’s bioavailability by increasing the surface area upon which oil-degrading bacteria can adhere. However, the curvature of the interface between oil droplets and water alters the area available to surfactants, complicating predictions of bacterial adsorption.

To better understand bacterial adhesion processes (using Marinobacter hydrocarbonoclasticus, a marine organism implicated in biodegradation) with different surfactants, the team prepared dodecane oil-in-water emulsions using co-flow microfluidic devices with droplet diameters observed during Deepwater Horizon. Using 3-D fluorescence images taken over times of up to three hours by a confocal microscope, the team counted the number of bacteria that adhered to the interface.

The authors noted that their laboratory experiments represent simplified conditions compared to actual marine biodegradation and that the results should be considered for optimal (i.e. minimal) application of surfactants or dispersants early in an oil spill scenario. For longer time scales, oil-metabolizing bacteria may be able to grow on the oil-water interface and continue modifying interfacial tension, further complicating predictions of oil biodegradation. They suggest that future research investigate how growth, bacterial exudates, motility, flow, and organic matter affect bacterial adhesion to the oil-water interface.

The Gulf of Mexico Research Initiative (GoMRI) is a 10-year independent research program established to study the effect, and the potential associated impact, of hydrocarbon releases on the environment and public health, as well as to develop improved spill mitigation, oil detection, characterization and remediation technologies. An independent and academic 20-member Research Board makes the funding and research direction decisions to ensure the intellectual quality, effectiveness and academic independence of the GoMRI research. All research data, findings and publications will be made publicly available. The program was established through a $500 million financial commitment from BP. For more information, visit http://gulfresearchinitiative.org/.